My 1377, vintage 1994, probably has never bee properly cleaned (or had much in the way of any other maintenance before I got it). I have followed advice here about oiling (just got a quart of non-detergent 30 oil, as suggested). Now about barrel: I am assuming there is some build up in it there of stuff that should be removed. Any advice on how to properly proceed would be moat appreciated!
Wallyworld has Umarex cleaning kits and sometimes they have .177 one piece cleaning rods.
I found the cable type pull through of the Umarex kit pretty much useless but the swabs and plastic bristle brushes work fine with my rod.
The plastic bristle brush is best to use when cleaning any barrel that you can't get to the breech end. The bronze brushes would get stuck trying to withdraw them.
I use lighter fluid as a solvent for pellet and oil residue, brushing well then swabbing, rinsing out the swab each time, then fire a few wads of tissue or cut off cotton swabs through the bore.
Don't oil the bore afterwards.
first thing I'd do is see if it shoots straight and is accurate if it is I'd get a roll your own cig filter add some oil to it and shoot it repeating twice then twice more with un oiled ones then check it against a target see it shoots straight still-you may need to put a few through it to test but that's the fun bit
if you know the barrel is full of crap take it off an give it a good pull through -if it's a 94 then it'll be a phase 2 with plastic breech but even if it has an early phase 1 barrel and breech remove the probe and pull through till clean then re lead it again the fun part
Was able to run a looped piece of thin braided nylon cord down from muzzle end and pull though some pieces of paper towel wit just a drop of oil on them, rolled into a thin tube. Took a few passes to get out what I think was most of the dark residue. So far, so good! Ad yeah, now off to the 'fun part!'